Panel unloading machines



D. w. HAN NABLE PANEL UNLOADING MACHINES June 23, 1959 I 5 Sheets-She'et 1 Filed June 24, 1955 Inven tor Daniel biker Hannable 0 0v u llllkllllll By his. Attorney June 23, 1959 D. w. HANNABLE 2,891,688

PANEL UNLOADING MACHINES Filed June 24, 19.55 5 SheetsSheet 2 in mental" Daniel Wall er Hannable By his Attorney June 23, 1959 D. W.YHANNABLE 2,891,688 j PANEL QNLOADING MACHINES I Filed June 24,1955 r 5 Sheets-Sheet 3 W //7 1 92V .H'. I I \7 k\\\\\\ Lw' I (34 I 100 ""F P P Inventor I E 7 7 v Daniel Walker Hannable 94 E "1 5 luv I B his Attorney i g a I June 23, 1959 D. w. HANNAB'LE 2,891,688

' PANEL UNLOADING MACHINES Filed June 24, 1955 5 Sheets-Sheet 4 Fig. 5

Inventor Daniel Walker Hannable By hi6 Attorney June 23, 1959 ,D. w. HANNABLE PANEL UNLCADING MACHINES 5 Sheets-Sheet 5 Filed June 24, 1955 Inventor Daniel Wzlker Hannable By his Attorney United States Patent Ofiice 2,891,688 Patented June 23, 1959 PANEL UNLOADING MACHINES Daniel Walker Hannable, Beverly, Mass, assignor to United Shoe Machinery Corporation, Flemington, N.J., a corporation of New Jersey Application June 24, 1955, Serial No. 517,730

2 Claims. (Cl. 214-310) This invention relates to means for successively removing work pieces from work supports, and more particularly to automatic machines for unloading detachably mounted chassis, such as fragile wiring board panels, from conveyorized pallets. Although the invention is accordingly herein illustrated as embodied in apparatus primarily designed for automatic assembly of electrical and electronic equipment, it will be appreciated that the invention is not thus limited in use, but may in several respects have advantageous application in other fields and when associated with various types of machinery.

A copending application filed September 27, 1954, in the names of Adolph S. Dorosz and Thomas W. Snow, Serial No. 458,328, now Patent No. 2,772,416, discloses a conveyor which may be employed to carry work supporting pallets in succession and simultaneously to and through a series of operating stations, the pallets being respectively positioned with their work at these stations and then released for conveyance to their respective succeeding stations. As there described, the conveyor is used to assemble electronic components in predetermined order on chassis in the form of printed wiring boards, each station thus being occupied, for example, by testing equipment, soldering, or other treating machines, and/ or component inserting machines, for instance of the type disclosed in a copending application filed September 27, 1954, in the names of Alderman et al., Serial No. 458,312. Portions of the machines fully described in these copending applications are included in the illustrative embodiment of the present invention and will be briefly referred to hereinafter. Automatic means for detachably mounting a panel or wiring board on each of the pallets to be conveyed is disclosed in a copending application filed May 25, 1955, in the name of Daniel W. Hannable, Serial No. 510,963, and shown as occupying an initial station along the conveyor line. In order that the work-supporting pallets may, after they have traversed the series of operating stations, be returned for re-use in the conveyor line, it is essential that the work pieces or panels mounted thereon be carefully removed, together with their assembled components, as units.

In view of the foregoing it is an object of this invention to provide in an assembly and/or treating system comprising a series of operating stations through which work pieces are successively carried by work supports, respectively, simple but effective means for detachably removing the successive work pieces operated on from the work supports and delivering the pieces consecutively in ordered arrangement to a given location, while their work supports are separately moved to another destination, for example into a container, or fed back toward the beginning of said system.

In keeping with the above-stated object and as a feature of the invention, the illustrative machine herein shown includes, in combination, a conveyor for carrying pallets successively, each pallet having means for detachably holding a wiring board thereon, means for positioning successive pallets at an unloading zone in juxtaposition to the conveyor, means engageable with the wiring board mounted on each positioned pallet to release the board from said holding means, and unloading mechanism including a receptacle pivotally mounted adjacent to the conveyor for receiving and removing the successively released wiring boards, said mechanism being operative in time relation to said board releasing means.

A further feature of the invention resides in the combination with reciprocable plungers for engaging and moving successive, detachably mounted work pieces heightwise from their respective supports, of an openbottomed receptacle movable heightwise with respect to the supports in time relation to said plungers, said receptacle comprising adjustably spaced guideway portions, each of said portions having a shelf disposed to be yieldingly displaced from operative position by the heightwise movement of a work piece, and an abutment mounted on said receptacle and engageable with the successive work supports to counter the thrust imparted thereto by the plungers when acting on said work pieces.

The above and other features of the invention, together with various novel details of construction and combinations of parts, will now be more particularly described in connection with an illustrative machine in which the invention is embodied, and with reference to the accompanying drawings thereof, in which:

Fig. 1 is a view in side elevation of a machine for automatically unloading detachably mounted wiring boards from conveyorized pallets, certain portions being broken away to reveal construction details, and a boardreceiving receptacle being indicated in two of its operating positions.

Fig. 2 is a plan view of the machine shown in Fig. 1 with portions broken away.

Fig. 3 is a vertical section taken on the line III-JII of Fig. 2.

Fig. 4 is a plan view of a wiring board and its pallet, together with portions of a conveyor system by which they are positioned and clamped in relation to the illustrative machine, a rearward part of which is shown.

Fig. 5 is a section taken on a line V--V of Fig. 4 and on an enlarged scale.

Fig. 6 is a section taken on the line VIVI of Fig. 4 and on an enlarged scale, and

Fig. 7 is a schematic wiring diagram illustrating an electrical circuit for controlling two consecutive operating stations along the conveyor system, one of said stations being occupied by the machine illustrative of this invention.

Since the pallet positioning and clamping means of the conveyor system shown with the exemplary pallet un-' loading machine for purposes of illustration has been fully disclosed in the above-mentioned Dorosz et al. application, only so much of said means will be hereinafter described as seems necessary or desirable to a clear understanding of the construction and operation of the machine. The latter, generally designated Z (Figs. 1 and 7), occupies for purposes of this illustration a regular through terminal (or nearly terminal) station in a series of operating stations spaced along the conveyor. An inserting machine, generally designated Y (Fig. 7) and of the type disclosed in the Alderman et al. application above cited, may be considered representative of equipment which might occupy a preceding station. Successive pallets 20 are conveyed by parallel endless belts 22, 22 (Figs. 1 and 4) to carry their respective detachably mounted wiring boards 24 from one station to the next. Each pallet is guided between stations and accurately located thereat by means of a pair of pins 26, 28 (Fig. 4) which project upwardly from a margin of the pallet and extend into a straight and continuous series of U-shaped guideway channel members 30 (Figs. 1 and 4) secured to the front of alined conveyor frame sections 32, only an upper portion of one being shown herein. These sections support the operating stations, the pallet control means referred to, and horizontal guide bars 34, 34, respectively underlying the continuously operative belts 22, 22. As indicated in Fig. 4, an advancing pallet, its wiring board having then received all, or substantially all, required component installation, testing, and treatment, is positioned and clamped at the station Z by being forced rearward by a lever 36 (Fig. 4) so that the trailing pin 26 abuts a stop 38 projecting in the channel member 30, and the advance pin 28 engages a plate 29 secured to the inner side of the member 39. Simultaneously with this pallet locating action the pallet is disassociated from the belts 22, 22 by riding up on a beveled back rail 41) afiixed to the rear bar 34 and by riding up on a flat topped cam insert 42 (Figs. 1 and 4) fast on a control bracket 44 adjacent to the front bar 34. The rearward margin of the pallet engages and displaces a pivotally mounted and spring-backed dampening detent 46 supported by a bracket which is screwed to the rear bar 34.

Pallets may differ in shape and other details suitably to accommodate different types of work to be operated upon, though it is preferable that the pallets used for a particular run of wiring boards be all alike. In order that boards of dilferent size and configuration may be mounted on a given group of similar pallets, the latter may have one or more corresponding internally projecting portions 48 (Fig. 4). The usually rather fragile Wiring boards to be removed will bear printed circuits (not shown) on at least one side thereof, will support various components on at least one (usually the opposite) side thereof, and are provided with spaced holes 51 52 (in this instance diagonally related, one indicated in Fig. and one in Fig. 6) for receiving round ended indexing pins 54, 56, respectively, doweled in the portions 48 of the pallets. These pins are relied upon to register the wiring boards mounted thereon in appropriate corresponding relation to the respective pallets and hence to the operating tools of the respective stations. Other registering means, snap fasteners for instance, may be applied to the pallets or, if preferred, to the wiring boards to obtain appropriate detachable mounting. For insuring that a wiring board is releasably held on the pins 54, S6, spring clips 58 (Figs. 5 and 6) have upturned latching ends 60 arranged to engage marginal portions of the board. Each spring clip 58 is yieldably secured to a board by a pin-and-slot connection, a split tail portion of the clip cooperating with a pin 62 in the pallet to permit yielding of the clip bodily. For the special use of the unloading machine Z to be described, each pallet is further provided with a hole 64 (Figs. 4 and 5) bored between each pin 54, 56 and its adjacent clip-latching end 61).

The illustrative machine has a frame 66 (Figs. 1, 2, and 3) that is mounted for adjustment about a vertical axis and laterally on a conveyor frame 32 to enable the machine to accommodate work pieces of different shape and when oriented in different ways upon the pal lets. Thus, a bar 68 (Figs. 1 and 3) extending across an opening 71) in the frame 32 threadedly receives a clamping bolt 72, the upper end of which is threaded into the base of the machine frame 66 and the lower end of which is provided with an operating handle (not shown). A front portion of the frame 66 is formed as a hollow cylinder to house work detaching or ejector mecha nism to be described, and a rearward portion extends upwardly to provide bearing supports 74, '74 for a pivotal shaft 76 controlling work receiving and removing means subsequently to be explained. Both the work ejecting mechanism and the work removing means are pneumatically actuated by an air cylinder or motor 78 (Fig.

1) in proper time relation to each other and to the cyclical pallet positioning and clamping means above referred to, the housing of the motor 78 being secured to a lower portion of the frame 66 and having connection via a pipe 80 and a three-way solenoid control valve 82 (Figs. 1 and 7) with a conduit 84 extending parallel to the conveyor and providing a suitable supply of air under pressure to the various. stations along the conveyor line. At the start of a cycle of operations at station Z, a pallet having arrived there for positioning, the valve 82 is automatically energized electrically by means later explained in connection with the electrical controls of the entire apparatus, and acts to admit air under pressure to the motor 78 to force its piston 36 (Fig. 1) upwardly against the resistance of a return spring 88, air delivery from the pipe 89 being subsequently cut off by the valve to terminate a power stroke of the piston 86 when an exhaust port is opened. The piston is connected to a vertical piston rod 90 (Fig. l and 3) the upper end of which is adjustably threaded into a coupling link 92 that centrally carries a transversely extending pin 94 (Figs. 1, 2, and 3). The latter extends horizontally through alined vertical slots 96, 96 (one shown) in the frame 66 and through shorter alined vertical slots 98, 98 (one shown) formed in a cylinder 1011 (Fig. 3) slidable heightwise in the cylindrical portion of the frame 66. An adapter plate 102 secured to the upper end of the cylinder 1M detachably supports a flat plate 104 of a shape suited to the particular configuration of the work pieces to be unloaded. For purposes later explained, the plate 104 is fitted with spaced stabilizer pins 186, 1116, and upstanding ejector pins 108, 108, the latter being respectively disposed to be thrust through the pallet holes 64 of a positioned pallet for endwise engagement with the underside of a wiring board thereon. The pins 106, 198 may be suitably shifted on the plate 104 to meet the requirements of differently shaped work pieces. Normally, the upper ends of these pins will lie in a plane.

Before the upward or power stroke of the piston 86 is effective to drive the pins 106 and 108 heightwise by causing the pin 94 forceably to engage the upper ends of the slots 98, 98, the pin 94 will commence to actuate mechanism for operating the work receiving and removing means above mentioned. For this purpose the opposite ends of the pin 94 are respectively received in corresponding slots 110, 111 formed in the lower ends of a pair of parallel bell crank levers 112, 112 (Figs. 1, 2, and 3) that are fulcrumed on a bearing pin 114 journaled in the frame 66. Upper extremities of the bell crank levers 112 are connected by a cross rod 116 upon which is slidably mounted in spaced relation a pair of composite links 118, 118 (Figs. 1, 2, and 3) adjustable in length and, in effect, yieldingly compressible lengthwise to afford a lost motion and dampening action. Referring to Fig. 3, each composite link 11% includes a left-hand link 120 provided with an open-ended cylindrical portion, a compression spring 122, a right-hand link 124 slidable within the cylindrical portion just referred to for receiving the other end of the spring 122, and an eye bolt or stud 126 threaded into the link 124. For adjustably loading the spring 122 initially the stud 126 has a sleeve 128 threaded thereon which passes through a snap ring 130 that engages an annular shoulder formed in the open end of the link 12%, the sleeve abutting the link 124. The stud 126 is pivotally connected to the lower end of an arm 132 which has its upper end fixedly secured on the shaft 76 by a set screw 134. Upward movement of the pin 94 accordingly is initially effective through the linkage described to rotate the shaft 76 counterclockwise, as viewed in Figs. 1 and 3, thereby similarly pivoting an open-bottomed receptacle generally designated 136, having side guideway portions 138, 138 that are fixedly supported on the shaft 76 for rotation assness therewith. These guideway portions 138 are axially slidable on the shaft 76 with respect to each other to accommodate difierent sizes of work pieces, as will be described. A rod 140 (Figs. 1, 5, and 6) mounted in the outer side of each portion 138 pivotally supports a depending lever 142 having an inwardly extending, narrow shelf portion 144 and an inclined cam surface 146. The levers 142, 142 are yieldingly urged toward each other by leaf springs 148 depending from the guideway portions 138 so that the portions 144 may occupy work supporting positions determined by abutment surfaces 150 (Fig. 5) formed on the portions 138, respectively.

The limit of upward pivotal movement of the receptacle 136 is adjustably determined by a stop screw 152 (Figs. 1, 2, and 3) threaded into one of the bell crank levers 112 and engageable endwise with the frame 66. Similarly, a stop screw 154 threaded through an arm 156 of the bell crank lever adjustably determines one limit of pivotal movement of the latter and tends to establish, through the spring 122, the lowermost, normally horizontal position of the receptacle. A stop screw 158 threaded through an arm 160 on the front of the receptacle 136 is arranged to engage an abutment 162 on the conveyor frame 32 and hence acts positively to fix the lowermost and work-receiving position of the receptacle. From the foregoing description it will be understood that the motor 78 is effective to lower the receptacle 136 to its horizontal work-receiving position, a stop screw 164 threaded into each of the guideway portions 138, then abutting the upper surface of the rearward margin of the positioned pallet 20 to prevent its upward displacement, whereupon the pin 94 acting on the cylinder 100 at the upper ends of the slots 98, 98 is caused by the motor to lift the cylinder 100 to thrust the ejector pins 108 through the pallet holes 64 respectively, and thereby release the wiring board from the laterally displaced spring clips 58 and raise the board to a maximum extent determined by the upper end of the slots 96, 96. During the latter part of the upward travel of the pin 94 the spring 122 becomes further compressed more firmly to hold the pallet against upward thrust. The stabilizing pins 106 cooperate with the pins 108 to move the board bodily heightwise, marginal edges of the board engaging the cam surfaces 146, 146, respectively yieldingly to pivot the levers 142 apart as indicated by phantom lines in Fig. 5 until the springs 148 can become effective to place the shelf portions 144 in work-supporting position beneath opposite marginal extremities of the wiring board.

Consistent with control mechanism disclosed in said Dorosz et al. patent and later explained in connection with the wiring diagram of Fig. 7, mechanism is provided whereby the pallets cannot be released from station Z and the preceding stations until after the pins 106, 108 have transferred a completed board to the receptacle 136 and returned to their lowermost positions. A time delay device generally designated 166 (Figs. 1, 2, and 7) of conventional type is employed to actuate the valve 82 and thereby relieve air pressure in the motor 78. The arrangement is such that the pins 106, 108 return to rest position before the receptacle 136 is raised. As indicated in Figs. 1 and 2, an arm 168 is secured to one of the bell crank levers 112 and is formed with an arcuate slot 170 provided for machine assembly purposes. Adjustably secured to the arm 168 by a clamping bolt 172 extending through the slot 170 is a bar 174 bored to receive the bolt and extending above the device 166. A stop screw 176 adjustably threaded in the bar 174 is arranged for engagement with a contact abutment 178 (Fig. 2) formed on the upper end of a spring-backed piston rod 180 (Figs. 2 and 7) of the time delay device. The screw 176 normally rises as fast as, or faster than, the rod 180 which moves upwardly at a rate adjustably controlled by a needle valve 182 (Fig. 7). Accordingly, a contact 184 on the rod 180 rises from a closed position in one electrical circuit to close another circuit after the receptacle 136 latter circuit is effective as later explained to energize a solenoid 186 controlling the valve 182 and thereby permits the loaded spring 88 to return the cylinder with the pins 106, 108 to their starting positions. Continued return influence of the spring 88 then further urges the bell cranks 112 counterclockwise, as viewed in Figs. 1 and 3, to tilt the receptacle upwardly with the wiring board resting upon the shelf portions 144. When the board has thus been raised by the receptacle and provided with sufiicient slope, the board will slide downwardly and rearwardly under the influence of gravity and pass over parallel fixed shoulders 188, respectively formed on the guideway portions 138, 138 to merge with the portions 144, 144, respectively. As herein shown, each completed wiring board assembly is further conducted, rear edge first, down a fixed chute 190 secured to the frame 66 for disposition, for instance, in a container or upon other conveyor means.

For several possible reasons, such as that the wiring boards are not always formed exactly alike though intended to be uniform, and perhaps because of extraneous particles interfering, one spring clip 58 may occasionally resist the ejecting movement of the pins 106,108, and then suddenly yield laterally at a different instant than does another spring clip 58, the consequence being that the wiring board being unloaded will be abruptly released for upward movement in a tilted position which, if not corrected, will permit the board to fall between the shelf portions 144. A similar tilting will occur if one side margin of the board engages a cam surface 146 before an opposite board margin can contact an adjacent surface 146. To insure that a board, if and when released in tilted position from a pallet, will be restrained against bouncing and be urged to assume a substantially horizontal position and thereby act to separate the shelf portions 144 and then land thereof, provision is made for flowing spaced currents of air downwardly to engage opposite side margins of the successively released wiring boards. Thus, a tube 192 (Figs. 1, 4, and 5) secured on each side guideway portion 138 has an orifice 194 (Fig. 6) to direct a somewhat concentrated air stream, the tubes 192 being connected by flexible hose 196 (Fig. 1) with a pipe 198 bleeding air from the pipe 80. The draft from the orifices 194 may be suitably modified by means of a valve 199 connected in the pipe 198.

A cycle of operations of the panel unloading machine will now be reviewed in connection with Fig. 7 and the electrical means for controlling the pallet positioning,

clamping, and releasing mechanism of the conveyor sys-'- tern. As above indicated, the pallets 20 are simultaneously positioned and clamped at their respective stations by the levers 36. As fully explained in said Dorosz et al. and Hannable applications, these levers are pivotally actuated, the system being automatically operable when a pallet occupies each station. Any necessary initial adjustments, such as positioning of the pins 106, 108 and spacing the side guideway portions 138 on the shaft 76 to enable the shelf portions 144 to support the particular work pieces to be unloaded will be presumed to have been made. In the event a wiring board or other Work piece has no parallel and opposite marginal portions, new levers 142 having shelf portions of different shape or other means may be provided in the receptacle to insure cooperation with the ejector means in effecting removal. Fig. 7 illustrates the positions of parts when no pallet is at a station, the receptacle 136 is in its rise position, and- 214 is provided to permit optional elimination of the operation of the unloading machine at station Z, a switch having contacts 216, 218, and 220 serving a similar function for station Y. A normally open switch 222 is used in initially arranging for a pallet to be locked at successive stations. Upon pallets arriving at stations Y and Z, pivotal signal levers 224 actuated by the respective pallets operate station limit switches 226, 228 of the pallet positioning and clamping mechanism, temporarily closing series contacts 232Y, 232Y, 232Z, 232Z. As a consequence, when the final one of the pallets being positioned has arrived at its station, a conveyor control rod 234 (Fig. 1) running nearly the length of the conveyor is shifted endwise simultaneously to operate the clamping levers 36. Thus, the closed contacts 230Y, 2301 and 230Z, 230Z Signal for pallet clamping by energizing a clamping control solenoid 236 (Fig. 7) governing a valve 238 which causes an air motor (not herein shown) to effect the required endwise shifting of the rod 234 against the resistance of a return spring, the energized solenoid 236 closing contacts 240, 242, and 244. The solenoid 236 is maintained energized by a circuit through the switch 208, the contacts 240 and 220, and a contact 246 hereinafter referred to. With the several pallets held clamped and positioned, the signal levers 224, under influence of return springs of the respective switches 226, 228, open the contacts 230Y, 230Y and 230Z, 2302 and close the contacts 232Y, 232Y and 232Z, 232Z to signal for operation of all stations as will next be explained.

The valve 82 (Figs. 1 and 7) is energized at the start of the cycle of the unloading machine by a circuit completed through the contacts 244, 210, 232Z, 2322, a latter mentioned contact 252, and the switch 204, air under pressure being admitted to the motor 78 as above described. Consequent upward movement of the pin 94 in the slots 98 lowers the receptacle 136 to horizontal work-receiving position. As the pin 94 thereafter bears on the upper ends of the slots 98, the stop screws 164, 164 yieldingly engage the locked pallet 20 more firmly, the spring 122 yielding for this purpose, and the cylinder 100 is raised to carry the pins 106, 103 upwardly into endwise engagement with the wiring board 24. The force thus applied to the board lifts it from the pins 54, 56, the latching ends 60 of the spring clips being yieldingly displaced laterally as indicated in Fig. 6 to release the board for continued upward movement against the stabilizing down drafts from the orifices 194. After the pins 106, 108 have raised the wiring board 24 sufficiently thus to pivot the levers 142 apart, the springs 148 cause the shelf portions 144 to resume their cooperative worksupporting positions beneath opposite margins of the board. Clockwise movement of the bell crank levers 112, as viewed in Figs. 1 and 3, and resulting from the upward movement of the pin 94, lifts the arm 168 and hence the stop screw 1%, thereby permitting the time delay contact 184 to rise to open one circuit and to close another circuit, the latter being effective through the contacts 244, 210, 2322, 232Z to energize the solenoid 186. The solenoid 186 acts to open the contacts 252 and 246 and to close contacts 254, 256. it should be noted that shifting of these contacts is simultaneous with similar shifting of corresponding contacts 258, 260, 262, and 264, all of which are controlled by a solenoid 266 associated with station Y and a valve 268 governing operation of operating instrumentalities, for example a driver bar 270 and anvil 272. (The solenoid 266 is energized on completion of a circuit through the contacts 244, 216, 232Y, 2321, and anvil switch 274- that closed upon in sertion of a component 276 and a contact 278 corresponding to the contact 184.) When the contact 252 opens, the valve 82 is de-energized permitting the spring 83 to retract the pins 106, 108 to their starting positions and then raising the receptacle 136 with the detached board 24, the contact 184 meanwhile returning to its lower circuit closing position. During the upward movement of the receptacle the solenoid 186 is maintained energized through a circuit including the contacts 244, 210, and 256. The completed work being free to slide under the influence of gravity down the shelf portions 144, the shoulders 188, and the chute 1%, the several pallets are unclamped for further conveyance by de-energizing the solenoid 236. This is done by energizing a solenoid 230 through a circuit, including the contacts 1.84 (now lowered), 254, 272'; (now lowered), 260, and a pallet unloading switch 282 that remains closed unless too many pallets accumulated at a pallet unloading or pallet return point along the conveyor line. Energizing the solenoid 280 results in its contact 284 opening a holding circuit to de-energize the solenoid 236 and hence unclamp the pallets, the detents 46 thereupon restoring them to the belts 22, 22 for further conveyance. Energizing the solenoid 280 further results in de-energizing the solenoids 186, 266 to return their contacts to the positions shown, the unloading machine then being ready to act on the next pallet and board arriving at station Z.

It will be apparent from the foregoing that this invention provides a highly useful auxiliary machine for separating and removing various sorts of work pieces from their respective conveyorized work-carrying supports.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. In apparatus for transferring electric component carrying chassis from pallets, said pallets being in the form of open, flat frames having means for detachably holding the respective chassis by their marginal edges in relatively fixed position, ejector mechanism operable through the opening in a pallet to release and separate a chassis therefrom, said mechanism including spaced pins respectively engageable with the chassis adjacent to said holding means, an open bottomed receiving support tiltable toward and from a receiving position in juxtaposition with the pallet, said support comprising shelf portions adapted yieldingly to be separated by engagement therewith of opposed margins of a chassis as it is separated from the pallet and having an abutment engageable with the pallet when the support occupies its receiving position to brace the pallet against thrust imparted thereto by said ejector mechanism, and power means for actuating said mechanism and support in time relation.

2. Apparatus as set forth in claim 1 and further characterized in that said power means includes a motor operatively connected to a source of air under pressure, and means mounted on said receiving support and in communication with said source is provided for directing a stream of air toward the successive chassis to be transferred to stabilize their movement.

References Cited in the file of this patent UNITED STATES PATENTS 2,217,983 Hopkins Oct. 15, 1940 2,386,076 Taylor et al Oct. 2, 1945 2,562,247 Van Schie July 31, 1951 2,623,626 Ditolla Dec. 30, 1952 2,639,050 Hoffmann, Jr. May 19, 1953 2,680,524 Snyder et a1. June 8, 1954 2,707,571 Smith, Jr May 3, 1955 

